Re: Time is what we measure with a clock.

Dick <remdickhm@xxxxxxxxxxxxx> wrote:

On Tue, 22 Aug 2006 17:43:28 +0200, nospam@xxxxxxxxxxxxxxxx (J. J.
Lodder) wrote:

Dick <remdickhm@xxxxxxxxxxxxx> wrote:

On Thu, 17 Aug 2006 23:09:49 +0200, nospam@xxxxxxxxxxxxxxxx (J. J.
Lodder) wrote:

Dick <remdickhm@xxxxxxxxxxxxx> wrote:

Heinz Pagels, "The Cosmic Code" in discussing "Special Theory of
Relativity" says space is what we measure with a rod and time is what
we measure with a clock.

A direct Einstein quote.
Einstein was reacting to the Newtonian idea of absolute time,
which was supposed to have a meaning indepent of measurement.

A clock: a sun dial, an hour glass, a pendulum clock, perhaps a wind
up wrist watch, oh, an atomic clock?

It shouldn't be taken too literally.
Time is the rate at which physical processes go,
therefore any physical process can serve as a clock.
(at least in principle)
So one may idealise to a 'clock' that is theoretically convenient.
Einstein's choice for the ideal clock was a pulse of light
being reflected between perfect mirrors a fixed distance apart.

Best,

Jan

I immeadiately noticed "Time is the rate at which physical processes
go...."

"Rate" is key, however, rate requires something to compare distance or
force with. We don't need rates if we compare to processes.

Comparing processes is the only thing you can do,
for a clock is also a physical process.

Jan

I can act on my own. I can run two processes simultaneously (horse
race) and visually determine the outcome without invoking a clock.

Every physical process can serve as a clock.
Some are better than others, but that is a practicality,

Jan

.

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